The present invention relates to apparatus for locally expanding ductile tubes of a heat-exchanger into fixed engagement with a supporting metal sheet having openings through which the tubes pass in laterally spaced parallel relation. The invention further relates to means for locating the position of a tube sheet with a probe positioned inside a tube passing through the sheet and for expanding the tube at the precise location where it passes through the sheet as part of the same operation, i.e., without withdrawing the probe from the tube.
In a common form of heat exchange apparatus such as condensers and evaporators in a variety of refrigeration units, a plurality of hollow tubes pass through openings in an essentially planar support sheet. Typically, a plurality of such sheets are provided at spaced intervals along the length of the tubes. Although the tubes are closely surrounded by the openings when axially inserted therethrough, it is necessary to form a tight, mechanical connection between the outer surfaces of the tubes and the portions of the sheet surrounding the openings, in order to eliminate tube vibration and resulting wear.
Since both the tubes and sheets, in order to provide efficient heat conduction, are normally formed of ductile metal, the connection is provided by expanding the tubes with an internal expansion device in the areas where they pass through the openings. It is necessary, of course, to position the expansion device at a predetermined location within the tube to ensure that expansion is effected in the plane of the support sheet. Thus, fabrication of heat exchange apparatus involving controlled expansion of a relatively large number of tubes at several axial locations can be a time-consuming task, requiring a skilled operator, representing a significant portion of the cost of such apparatus.
The principal object of the present invention is to provide apparatus for improving the efficiency, and thus reducing the cost, of fabricating heat exchange devices wherein hollow, elongated tubes are expanded into tight engagement with support sheets.
Another object is to provide novel and improved apparatus for effecting localized, radial expansion of a hollow, elongated tube of ductile metal at a desired axial location.
Other objects will in part be obvious and will in part appear hereinafter.